1. Field of the Invention
The present invention relates to novel aryl ethynyl phthalic acid derivatives useful for functional materials such as medical and agricultural intermediates and liquid crystal and electronic materials, and to a method for producing the aryl ethynyl phthalic acid derivatives.
2. Description of the Related Art
Aryl ethynyl phthalic acid derivatives are important compounds as the starting materials of functional materials such as medical and agricultural intermediates and liquid crystal and electronic materials and, particularly, have recently received attention as subjects of research relating to various types of functional materials which utilize a carbon-carbon triple bond present in a molecule. For example, phenyl ethynyl acid anhydrides are used as terminal end-blocking agents which impart thermal curability, thermal resistance and acid resistance to polyimide oligomers as described in, for example, U.S. Pat. No. 5,567,800; Polymer, vol. 35, pp. 4874 to 4880, 1994 (hereinafter, referred to also as “Non-Patent Document 1”); ibidem, vol. 35, pp. 4857 to 4864, 1994 (“Non-Patent Document 2”); and Functional Materials, vol. 20, No. 12, pp. 33 to 40, 2000. Further, various types of method for producing phenyl ethynyl phthalic anhydrides are described in, for example, JP-A Nos. 11-180970 (“Patent Document 2”) and 2003-73372 (“Patent Document 3”), High Performance Polymer, vol. 6, p. 423, 1994; and Polymer Preprints, vol. 35, p. 353, 1995. However, these are not always satisfactory in terms of yield, efficiency or purity.
Accordingly, development of a novel compound in which performance required for a functional material such as a terminal end-blocking agent is improved and of a method for producing a phenyl ethynyl phthalic anhydride with high purity and high yield are in high demand.
Fluorine-containing aryl ethynyl phthalic acid, an alkali metal salt of fluorine-containing aryl ethynyl phthalic acid and fluorine-containing aryl ethynyl phthalic anhydride have been reported in an extremely small number (see, for example, Non-Patent Document 1). Accordingly, in terms of using these compounds as raw materials to provide resin materials with the desired properties, the range of choice is limited.